1. Field of the Invention
The present invention relates to a display apparatus.
2. Description of the Related Art
An organic electroluminescent(EL) display apparatus is a new type of flat panel display and formed from an array of organic light-emitting diode(OLED) devices. In general, an OLED device is comprised of an electrode serving as the anode, an electrode serving as the cathode and several thin organic layers sandwiched between these two electrodes. The organic layers include at least one emission layer containing more than one fluorescent or phosphorescent organic compound to emit light at each emission color. Applying voltage to the OLED device, holes and electrons are injected from the anode and the cathode, respectively, and form excitons in the emission layer. Then these excitons recombine and release their energy as emission of light.
In such an OLED device, it is proposed that emission efficiency be enhanced or chromaticity be adjusted using interference effects of light. For example, U.S. Pat. No. 6,541,130 proposes that a film thickness of an organic layer formed between an emission layer and a reflective electrode be adjusted to increase interference.
Also in Appl. Phys. Lett., Vol. 81, p. 3921 (2002), for example, a cavity structure, which is consisted of two reflection surface, is proposed to enhance light emission or adjust light emission chromaticity. One reflection surface is a reflective electrode and the other is an interface between a transparent electrode located on the side from which light is extracted and air.
Further, in Appl. Phys. Lett., Vol. 88, p. 073517 (2006) or the like, a cavity structure is proposed to enhance light emission or adjust light emission chromaticity between a metal translucent electrode located on the side from which light is extracted and a reflective electrode.
However, in the aforementioned technologies, the film thickness of an organic layer, a thickness of the transparent electrode or the like needs to be changed for each emission color, which leads to a problem in that a manufacturing process of the display apparatus becomes more complicated.